The present invention relates to sanitary ware such as washhand basins, wash bowls, urinals, stools, toilet tanks, toilet strainers, and the like.
Such sanitary ware as washhand basins, wash bowls, urinals, stools, toilet tanks, toilet strainers, and the like are daily necessities, and are required to have such a sufficient mechanical strength that even a very heavy person can use, while resting the person""s weight, some of these articles without anxiety. In addition, a good quality of design is also required.
Furthermore, the above mentioned commodities are used in the portions of a house where water is used, and hence these commodities are required to have chemical stability.
Accordingly, from old times, glazed ceramic wares have been used as sanitary ware, and particularly, glazed ironstone bodies and glazed vitrifiable bodies have been generally used for sanitary ware which bodies can be fired at such temperatures 1100 to 1300xc2x0 C. that easily allow to acquire in a single firing the degree of freedom in design based on the coloring and patterns brought forth by the glaze layer, and which bodies can also display sufficient mechanical strengths.
As for the ironstone bodies and vitrifiable bodies, however, when these bodies are fired to shrink to such an extent that a satisfactory mechanical strength is displayed, the shrinkage when fired becomes large and the deformation when fired also becomes great.
Accordingly, it is difficult to design accurately the dimension and shape of a product after being subjected to firing, and hence there are restrictions on the degree of freedom in giving design qualities and functionalities relying on shape.
In addition, depending on the shape of a product, the shrinkage and deformation cause generation of cracks, unevenness in shape, and degradation in dimensional accuracy, and hence sometimes become a source for lowering the process yield.
Furthermore, molded bodies being large in volume, thereby the setting efficiency gets worse, and the productivity cannot be said to be sufficiently satisfactory.
Accordingly, the object of the present invention is to provide the sanitary ware for which it is possible to accurately design the shape and dimension of a product after being subjected to firing while maintaining the mechanical strength required to sanitary ware, degradation of the process yield caused by shrinkage and deformation scarcely occurs, and the setting efficiency and productivity are improved as compared to the prior art.
The present invention provides, for the purpose of solving the above described problems, the sanitary ware, which is formed of a ceramic body with a glaze layer formed on the desired portions of the body, characterized in that the body is the one containing a crystal phase mainly composed of mullite and quartz, a glass phase mainly composed of SiO2 and Al2O3, and a crystal phase comprising those minerals selected according to need from cristobalite, andalusite, sillimanite, kyanite, and corundum; the main components of the body are 50 to 65 wt % SiO2, 30 to 45 wt % Al2O3, 0.1 to 2 wt % alkali oxides, and 0.1 to 10 wt % divalent metal oxides, the divalent metal oxide component containing at least the CaO component; and the CaO component segregation portions where the CaO component is segregated are dispersed in the body.
Since the CaO component segregation portions where the CaO component is segregated are dispersed, it becomes possible to provide the sanitary ware for which the firing shrinkage is sufficiently small while maintaining the mechanical strength required to sanitary ware, so that it is possible to accurately design the shape and dimension of a product after being subjected to firing; and the degradation of the process yield caused by shrinkage and deformation scarcely occurs, and the setting efficiency and productivity are satisfactory.
The reason for the above description can be interpreted as follows. Since the CaO component segregation portions where the CaO component is segregated are dispersed, the shrinkage caused by sintering of the liquid phase is suppressed in the segregation portions, and hence the firing shrinkage is suppressed. Furthermore, owing to the presence of the CaO component segregation portions which portions are different in such mechanical properties as Young""s modulus and the like, the crack deflection effect takes place, and consequently the mechanical strength can take a sufficient value.
In the preferred embodiments of the present invention, the above described crystal phase is dispersed in the above described glass phase, and the composition ratio of the glass phase to the body is smaller than 60 wt %.
By suppressing the glass phase ratio to be smaller than 60 wt %, the large shrinkage following the liquid phase sintering is suppressed, and accordingly the firing shrinkage can be suppressed to be 6% or below.
In the preferred embodiments of the present invention, the relationships between the abundance ratios of Ca to Na, K, and Mg (in weight ratios) in the CaO component segregation portion are made to satisfy all the relations, Ca greater than Na, Ca greater than K, and Ca greater than Mg.
Accordingly, the components in the CaO component segregation portion are largely different from the components in the glass phase, so that the effect due to the dispersion of the CaO component segregation portions is accentuated.
In the preferred embodiments of the present invention, the content of the CaO component in the body is made to be 1 wt % or above.
By making the content of the CaO component to be 1 wt % or above, an excellent ratio of the bulk specific gravity to the strength can be obtained. This is interpreted to be ascribable to the observation that when the CaO component is abundant, the shrinkage in the glass phase following the liquid phase sintering is suppressed to be small.
In the preferred embodiments of the present invention, the relationships between the CaO component and the other divalent metal oxide components in the above described body are made to satisfy the condition that in relation to 100 parts by weight of CaO, the other divalent metal oxides are 50 parts by weight or below.
Consequently, an excellent ratio of the bulk specific gravity to the strength can be obtained. This is interpreted to be ascribable to the observation that when the CaO component is abundant, the shrinkage in the glass phase following the liquid phase sintering is suppressed to be small.
In the preferred embodiments of the present invention, the content of quartz in the body is made to be 20 wt % or below.
Consequently, it becomes possible to suppress the excessive increase in the thermal expansion coefficient of the body, and hence the cracks are scarcely caused to occur in such products large in size and complex in structure as sanitary ware during the temperature decrease process in firing.
In the preferred embodiments of the present invention, when corundum is contained in the body, the content of corundum is made to be 20 wt % or below.
Since corundum has a high Young""s modulus, by uniformly dispersing corundum, a large effect of improving the strength can be obtained.
When corundum is contained in the body, it is preferable to make the corundum content be 20 wt % or below. The specific gravity of corundum is larger than the other minerals and glass phase, and hence when the body contains more than 20 wt % of corundum, the specific gravity of the body becomes heavy, resulting in an increase in cost when processing the bodies.
The present invention provides the sanitary ware which can be produced by the method comprising the process for molding the body raw material, the process for applying glaze, according to need, onto the desired portions, and the process for firing at the temperatures 1100 to 1300xc2x0 C., and which are characterized in that the body raw material contains a clay mineral, quartz, a raw material containing alkali metals, and a raw material containing divalent metals; the clay mineral is a mineral which contains at least one mineral selected from kaolinite, dickite, halloysite, sericite, and pyrophyllite; the raw material containing divalent metals contains at least one mineral of wallastonite, limestone, and anorthite; the content of quartz is 30 wt % or below in relation to the body raw material; the content of the clay mineral material is 30 to 90 wt % in relation to the body raw material; and the body raw material is controlled in size so that the average grain size based on a laser diffraction grain size analyzer is 3 to 10 xcexcm.
The use of at least one of wallastonite, limestone, and anorthite as a body raw material for use in introducing CaO, makes the CaO component segregation portions tend to be easily formed in a fired body, since in these materials the CaO component does not form solid solutions or compounds with such components as MgO, Na2O, K2O, and the like.
Accordingly, it becomes possible to provide the sanitary ware for which it is possible to accurately design the shape and dimension of a product after being subjected to firing while maintaining the mechanical strength required to sanitary ware with firing shrinkage sufficiently small, degradation of the process yield caused by shrinkage and deformation scarcely occurs, and the setting efficiency and productivity are improved as compared to the prior art.
The present invention provides the sanitary ware which can be produced by the method comprising the process for molding the body raw material, the process for applying glaze, according to need, onto the desired portions, and the process for firing at the temperatures 1100 to 1300xc2x0 C., and which are characterized in that the body raw material contains a clay mineral, quartz, a raw material containing alkali metal oxides, a raw material containing divalent metal oxides, and a raw material small in ignition loss; the clay mineral is a mineral which contains at least one mineral selected from kaolinite, dickite, halloysite, sericite, and pyrophyllite; the content of quartz is 30 wt % or below in relation to the body raw material; the content of the clay mineral is 30 to 90 wt % in relation to the body raw material; the content of the raw material small in ignition loss is 5 to 50 wt % in relation to the body raw material; and the body raw material is controlled in size so that the average grain size based on a laser diffraction grain size analyzer is 3 to 10 xcexcm.
The inclusion of the raw material small in ignition loss serves to reduce the firing shrinkage based on the ignition loss.
In the preferred embodiments of the present invention, the raw material containing divalent metals is made to contain at least one mineral of wallastonite, limestone, and anorthite.
The firing shrinkage is further reduced to yield an excellent strength through the multiplier effect between the effect of the use of a raw material small in ignition loss and the effect of the use of at least one mineral of wallastonite, limestone, and anorthite as a body raw material for use in introducing CaO.
In the preferred embodiments of the present invention, the raw material small in ignition loss is chamotte, and the main components of chamotte are each at least one mineral selected from mullite, cristobalite, quartz, and corundum, and the content of CaO in chamotte is set to be 1 wt % or above.
Through using a crystalline chamotte having the content of CaO of 1 wt % or above, the mechanical strength is improved by the crack deflection action, and the firing shrinkage rate becomes able to be reduced owing to the reduction in the content ratio of the glass phase.
In the preferred embodiments of the present invention, the raw material small in ignition loss is a hollow glass in which SiO2 and Al2O3 are the main components.
Accordingly, the pores in a hollow glass remain as closed pores in a body, and hence a body can be obtained which has a small bulk density for its strength.
In the preferred embodiments of the present invention, the raw material small in ignition loss is the one selected from shirasu-balloon, expanded perlite, and expanded shale.
Accordingly, the pores in the hollow glass remain as enclosed pores in a body, and hence a body can be obtained which is small in bulk density for its strength.
In the preferred embodiments of the present invention, the bulk density (Db) of the above described body is 1.6 to 2.1 g/Cm3, and the relationship between the bulk density and the bending strength (Sb) of the body is made to be such that Sb greater than 60xc3x97Dbxe2x88x9260 (MPa).
Consequently, the balance between the weight reduction and the mechanical strength can be maintained in a practical level for sanitary ware.
The present invention provides the sanitary ware which is made of a ceramic body and a glaze layer formed on the desired portions thereof, and can be produced by the method comprising the process for molding the body raw material, the process for applying glaze, according to need, onto the desired portions, and the process for firing at the temperatures 1100 to 1300xc2x0 C., and which is characterized in that the firing shrinkage rate along the lengthwise direction in the firing process is 6% or below; the softening deformation of the body in the firing process is 10 mm or below; the bulk density (Db) of the body is 1.6 to 2.1 g/cm3; and the relationship between the bulk density and the bending strength (Sb) of the body is such that Sb greater than 60xc3x97Dbxe2x88x9260 (MPa).
Consequently, the balance between the weight reduction and the mechanical strength and a degree of freedom in design can be maintained in a practical level for sanitary ware.
In the preferred embodiments of the present invention, the glaze layer is formed with such a glaze that gives a glaze layer smaller by 0 to 30xc3x9710xe2x88x927/xc2x0 C. in thermal expansion coefficient than the body.
By forming a glaze layer on the surface of a body, which layer is smaller by 0 to 30xc3x9710xe2x88x927/xc2x0 C. in thermal expansion coefficient than the body, the minute cracks due to aging on the surface of the glaze layer get to scarcely occur.
In the preferred embodiments of the present invention, the glaze layer of a transparent glaze is formed on the surface of the ceramic body.
Accordingly, the surface design quality is improved and adhesion of dirt onto the surface of the glaze layer is impeded, improving the resistance to dirt adhesion.
In the preferred embodiments of the present invention, a glaze layer of a coloring glaze is formed on the surface of the ceramic body, and furthermore, a surface glaze layer of a transparent glaze is formed thereon.
Consequently, the quality of surface design is improved, and adhesion of dirt onto the surface of the glaze layer is impeded, improving the resistance to dirt adhesion. In addition, the minute cracks due to aging on the surface of the glaze layer get to scarcely occur.
In the preferred embodiments of the present invention, engobe is formed on the surface of the ceramic body, and a glaze layer of the coloring glaze is formed thereon.
Consequently, the minute cracks due to aging on the surface of the glaze layer become to scarcely occur.
In the preferred embodiments of the present invention, engobe is formed on the surface of the ceramic body, and a glaze layer of the transparent glaze is formed thereon.
Consequently, the surface design quality is improved, and adhesion of dirt onto the surface of the glaze layer is impeded, improving the resistance to dirt adhesion. In addition, the minute cracks on the surface of the glaze layer due to aging get to scarcely occur.
In the preferred embodiments of the present invention, engobe is formed on the surface of the ceramic body, and a glaze layer of the coloring glaze is formed thereon, and furthermore, a glaze layer of the transparent glaze is formed thereon.
Consequently, the surface design quality is improved, adhesion of dirt onto the surface of the glaze layer is impeded, improving the resistance to dirt adhesion. In addition, the minute cracks on the surface of the glaze layer due to aging get to scarcely occur.
In the preferred embodiments of the present invention, the surface roughness Ra of the surface of the transparent glaze layer is made to be 100 nm or below, and preferably 70 nm or below, and more preferably 40 nm or below, as measured with a stylus-type surface roughness analyzer (JIS-B0651).
Consequently, adhesion of dirt onto the surface of the glaze layer is impeded, improving the resistance to dirt adhesion. In addition, the minute cracks on the surface of the glaze layer due to aging get to scarcely occur.
In the preferred embodiments of the present invention, the engobe formed between the body surface and the coloring glaze layer is made to be a fine layer smaller in porosity than the body.
Accordingly, the engobe gets to acquire the blocking function to prevent the gas generated in the body from passing through the glaze layer to grow as pinholes, and hence the poor exterior appearance such as speckles gets to be scarcely invited, and simultaneously the flatness and smoothness of the glaze layer surface is prevented from being deteriorated by the effect of the gas. In addition, the minute cracks due to aging on the glaze layer surface get to scarcely occur.
In the preferred embodiments of the present invention, a powder raw material having a 50% grain size (D50) of 6 xcexcm or below is used as the raw material for forming the engobe.
Accordingly, the engobe gets to easily form a fine layer smaller in porosity than the body layer, and to easily acquire the function to block the gas generated from the body.
In the preferred embodiments of the present invention, the raw material for use in forming the engobe has the composition of 30 to 50 wt % pottery stone, 30 to 50 wt % clay, and 10 to 30 wt % flux.
Consequently, the engobe tends to easily have a properly vitrified state and a properly sintered state, and gets to acquire stably the function to block the gas from the body.
In the preferred embodiments of the present invention, the thermal expansion coefficient of the body is 50 to 90xc3x9710xe2x88x927 (/xc2x0 C.) (50 to 600xc2x0 C.).
By making the thermal expansion coefficient to be 90xc3x9710xe2x88x927 (/xc2x0 C.) or below, cracking gets to scarcely occur in such products large in size and complex in structure as sanitary ware during the temperature decrease process in firing.
In addition, by making the thermal expansion coefficient to be 50xc3x9710xe2x88x927 (/xc2x0 C.) or above, it becomes possible to acquire a degree of freedom in designing glaze layer under the condition that cracking and the like scarcely occur.
In the preferred embodiments of the present invention, the molding method adopted is the slip casting method.
Accordingly, large-sized and complex sanitary ware can be easily produced at a low cost.